Walkway device and method for quantitative analysis of gait and its modification in rodents

ABSTRACT

A system and method for quantitatively assessing the changes in control of asymmetric locomotor behavior of an animal comprising analyzing the phase modulation in response to imposed asymmetric stepping tasks for quantitatively assessing changes in control of asymmetric locomotor behavior. A walkway gait device is provided comprising an elevated grid having at least one platform having a face and at least two or more pegs located in front or back of said platform, wherein each peg has a pressure sensor or switch in communication with a detection unit for capturing the pressure detected by one or more of the pressure sensors or switches. Preferably, the grid of the walkway gait device has at least three platforms to form a closed path loop.

CROSS-REFERENCE TO RELATED APPLICATIONS

This utility patent application is a divisional patent application ofand claims the benefit of co-pending U.S. patent application Ser. No.15/259,216, filed Sep. 8, 2016, which claims the benefit of U.S.Provisional Patent Application Ser. No. 62/215,977, filed Sep. 9, 2015.The entire contents of U.S. patent application Ser. Nos. 15/259,216, and62/215,977 are incorporated by reference into this utility patentapplication as if fully written herein.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

This invention was made with government support under grant numberU54GM104942 awarded by the National Institute of Health/NIGMS, and grantnumber P20GM109098 (CoBRE) awarded by the National Institute of Health.The government has certain rights in this invention.

FIELD OF THE INVENTION

Embodiments disclosed herein relate to devices and methods forquantitative analysis of gait, and in particular devices and methodsthat are able to impose and measure symmetric and asymmetric gaits withstride lengths that span the range from preferred to critical unstablelengths.

BACKGROUND OF THE INVENTION

Typical gait analysis devices and methods can provide overall evaluationof motor impairment due to disease or trauma. An example of an existingsystem can be obtained from Noldus (http://www.noldus.com/CatWalk-XT/)for $48,170, which may include analysis software and a device. TheNoldus CatWalk™ XT may be based on the Ladder Run Walking test or task,which can include: 1) footprint outline (print area, stand index,intensity); 2) distances between footprints (base of support, stridelength); and, 3) time relationships between footprints (cadence, supportand swing duration). The device may automatically detect the timing ofgait phases in self-paced locomotion. Noldus CatWalk™ XT software mayfurther provide qualitative and quantitative analysis of individualfootfall parameters. Yet, one deficiency exhibited by this and similarsystems is the lack of capability to instruct animals about a desiredpattern of locomotion.

The Ladder Rung Walking task/test had been developed for mice (Farr:2006) and for rats (Metz: 2009) to test the control of paw placementthat had been impaired after suffering damage to the corticospinalpathways. The task/test tends to rely on methods to impose bilateralpattern of locomotion without any means to control which limb is used tostep on rungs. For reasons explained below, this can lead todeficiencies in existing gait analysis devices and methods.

Behavioral assays can be used for assessing sensorimotor impairment inthe central nervous system (CNS). One of the more sophisticated methodsfor quantifying locomotor deficits in rodents can be to measure minutedisturbances of unconstrained gait overground (e.g. manual the Basso,Beattie, and Bresnahan (BBB) locomotor scale or automated CatWalk).However, cortical inputs are not required for generation of basiclocomotion produced by the spinal central pattern generator (CPG). Thus,unconstrained walking tasks, such as those relied upon by existing gaitdevices and methods, only indirectly test for locomotor deficits causedby motor cortical impairment.

Post-stroke morbidity in a surviving population may include gross motorimpairments that can pose a challenge for quantitative evaluation inboth post-stroke humans and animal models of neurologic impairment.¹ Forexample, in a clinical setting, these motor impairments are typicallymeasured using subjective criteria, which tend to be more sensitive tosevere impairment rather than moderate impairment. Yet, a majority ofsurviving patients exhibit moderate impairment as opposed to severeimpairment. In addition, assessments of post-injury motor behavior inanimals commonly use subjective assessment techniques (e.g. BBBlocomotor scale method) to generate the subjective criteria alluded toabove.^(2,3) While these subjective evaluation methods may assist withtranslation between gait rehabilitation studies in quadruped animalmodels and humans, such methods may not be as effective for assessingdetails of motor deficits associated with activity of separate musclegroups. This is compounded with the fact that the assessment of motorcortical contribution to locomotion (the putative culprit of motordeficit in cerebrovascular accident) may only be obtained indirectlywhen using such techniques, even when employing advanced automatedquantitative methods.^(4,5) Again, this can be due to such techniques'heavy reliance on open-field or linear walking tasks.

Open-field or linear walking tasks may not require corticalcontribution, and thus can be performed by the neural mechanisms of thespinal cord, i.e. the CPG network. Yet, the CPG network is typicallyspared in most animal models of neural damage, e.g. spinalizedanimals⁶⁻⁸. This is in spite of the fact that essential corticalcontribution to these spinal mechanisms had been experimentallyimplicated in tasks that require anticipated postural adjustments⁹ andreaching¹⁰, as well as precise stepping¹⁰.

Moreover, most neurological damage is asymmetric. For example, strokegenerally causes hemiparesis, e.g. weakness on one side of the body,which can result in an asymmetric gait.¹¹⁻¹⁴ The asymmetry of hemiplegicgait can be produced by asymmetric spatiotemporal muscle activation mostsignificantly manifested in the shortening of the extensor-associatedstance phase and the lengthening of the flexor-associated swing phase ofthe step cycle on the paretic side.^(15,16) This trend has not yet beenexplored across a range of locomotor speeds in healthy or pareticanimals.

The present invention is directed toward overcoming one or more of theabove-identified problems.

SUMMARY OF THE INVENTION

Spinal cord injuries and/or stroke often produce asymmetric motordisabilities that reduce biomechanical efficiency. Rodents can be defacto models for the biomedical research of neural trauma, and systemsand methods using rodents have been developed to assess biomechanicalefficiency. Yet, artisans have failed to provide systems and methodsthat can effectively analyze the details of sensorimotor control fromrodent behavioral performance. Prior to the date of this invention, nocommercial device or method is available that is able to imposesymmetric and asymmetric gaits with stride lengths that span the rangefrom preferred to critical unstable lengths. Moreover, no existingdevice or method has been able to provide an easy-to-learn task that canchallenge either stereotypical pathways of the spinal cord and/or thedescending neural pathways responsible for the precise limb placement.

In one embodiment of this invention, a walkway device including a framehaving pegs with a sensor array is provided. In another embodiment, amethod can include a training paradigm is provided. In some embodiments,the sensor is a 3D printable sensor enclosure. In at least oneembodiment of this invention, a device to modify systematically gaitparameters and to evaluate locomotor performance in animals, forexample, in rodents, is provided. Other devices for gait analysis inrodents do not have means to impose step restrictions for testingrehabilitation interventions after injury or basic research. Yet, theinventive device and method can impose desired stride length, interlimbphase, and an incline of locomotor path. In addition, the duration oflocomotor phases can be automatically measured and logged for furtherthe assessment of impairment or function.

As used herein, the term animal refers to any member of the animalkingdom, including for example, but not limited to rodents and Homosapiens.

In an exemplary embodiment, a method for quantitatively assessing thechanges in control of asymmetric locomotor behavior of an animal caninclude analyzing the phase modulation in response to imposed asymmetricstepping tasks as set forth in this application for quantitativelyassessing changes in control of asymmetric locomotor behavior. Themethod can further include observing changes in whole body coordinationof said animal requiring diagonal coupling between contralateralforelimbs and hind-limbs of said animal characterized by differences indiagonal angle. The method can further include providing an animalhaving either a focal stroke or spinal cord hemilesion.

In an exemplary embodiment, a walkway gait device can include anelevated grid (framework) having at least one platform having a face andat least two or more pegs located in front or back of said platform,each peg having a face and at least one side that extends verticallyfrom said face, said face of said peg positioned in proximity to saidface of said platform, including wherein each peg has a pressure sensoror switch, wherein one or more of said pressure sensors or switches arein communication with a detection unit for capturing the pressuredetected by one or more of said pressure sensors or switches. In someembodiments, one or more said pegs can be adjusted in one or more of ahorizontal, a lateral, or a vertical direction relative to said face ofsaid platform. In some embodiments, said platform and at least two pegscan be located in succession of each other relative to said platform,and a second platform located in juxtaposition to a peg that can belocated farthest from said platform such that the pegs are located andspaced between said platform and said second platform. In someembodiments, one or more said pegs may be adjusted in one or more of ahorizontal, a lateral, or a vertical direction relative to said face ofsaid platform and said face of said second platform. In someembodiments, said grid can contain at least three platforms each havingits own face and wherein each platform is separated from each other byat least two of said pegs, such that said three or more platforms form aclosed loop path. In some embodiments, one or more said pegs may beadjusted in one or more of a horizontal, a lateral, or a verticaldirection relative to said face of said platform. In some embodiments,the face of at least one of said pegs may be tilted up or down relativeto the face of another peg or the face of at least one or more of saidplatforms.

Another exemplary embodiment can include any of the methods or walkwaygait devices as set forth in the attached specification.

In another exemplary embodiment, a device for quantitative analysis ofgait can include a support framework structured to support a pluralityof pegs, the plurality of pegs forming a walkway to accommodate ananimal walking along the plurality of pegs, the walkway comprising afirst distal end and a second distal end. The device can further includea rest platform located at each of the first distal end and the seconddistal end. The device can further include at least one sidewall affixedto the support framework adjacent the walkway. The device can furtherinclude a path defined by the walkway and the at least one sidewall, thepath comprising a central pathway running along its center from thefirst distal end to the second distal end forming a path first side anda path second side. The device can further include at least one sensorand at least one detection unit associated with at least one peg, the atleast one sensor generating a signal when a foot by the animal is placedon the at least one peg and transmitting the signal to the detectionunit, the detection unit detecting placement of the foot by the animalon the at least one peg. In some embodiments, each peg can include aplatform section upon which the animal places the foot when walkingalong the path. In some embodiments, the plurality of pegs can bearranged in a linear array along the path and each peg may be arrangedin a staggered manner so that the platform section of each adjacent pegin the linear array may be located on an opposite side of the centralpathway. In some embodiments, a distance between each adjacent platformsection can be (d) and a distance between each consecutive platformsection of a same side of the central pathway can be a stride-length(SL). In some embodiments, placement of each peg relative to other pegsand relative to the support framework can be adjustable.

In another exemplary embodiment, a device for quantitative analysis ofgait can include a support framework configured as a square structure tosupport a plurality of pegs, the support framework comprising a firstside-length, a second side-length, a third side-length, and a fourthside-length, the plurality of pegs forming a walkway along eachside-length to accommodate an animal walking along the plurality ofpegs, each walkway comprising a distal end located at each corner of thesupport framework. The device can further include a rest platformlocated at each corner. The device can further include at least onesidewall affixed to the support framework adjacent each walkway. Thedevice can further include a path defined by each walkway and the atleast one sidewall adjacent thereto, the path comprising a centralpathway running along its center from the distal ends of each walkwayforming a path first side and a path second side. The device can furtherinclude at least one sensor and at least one detection unit associatedwith at least one peg within each walkway, the at least one sensorgenerating a signal when a foot by the animal is placed on the at leastone peg and transmitting the signal to the detection unit, the detectionunit detecting placement of the foot by the animal on the at least onepeg. In some embodiments, each peg can include a platform section uponwhich the animal places the foot when walking along the path. In someembodiments, the plurality of pegs can be arranged in a linear arrayalong the path and each peg can be arranged in a staggered manner sothat the platform section of each adjacent peg in the linear array maybe located on an opposite side of the central pathway. In someembodiments, a distance between each adjacent platform section can be(d) and a distance between each consecutive platform section of a sameside of the central pathway can be a stride-length (SL). In someembodiments, placement of each peg relative to other pegs and relativeto the support framework can be. In some embodiments, the (d) and the(SL) on an individual path are at least two parameters that can define acondition.

In some embodiments, the condition for the path of the first side-lengthcan be different from the condition for the path of the secondside-length, the condition for the path of the third side-length, andthe condition for the path of the fourth side-length. In someembodiments, the condition for the path of the second side-length can bedifferent from the condition for the path of the first side-length, thecondition for the path of the third side-length, and the condition forthe path of the fourth side-length. In some embodiments, the conditionfor the path of the third side-length can be different from thecondition for the path of the first side-length, the condition for thepath of the second side-length, and the condition for the path of thefourth side-length. In some embodiments, the condition for the path ofthe fourth side-length can be different from the condition for the pathof the first side-length, the condition for the path of the secondside-length, and the condition for the path of the third side-length. Insome embodiments, the condition is a set of parameters to evaluatelocomotion performance, impose step restrictions, and/or trackcorticospinal function.

In another exemplary embodiment, a method for quantitative analysis ofgait can include constructing a device, generating at least one pathalong which an animal is forced to walk during at least one walkingcampaign. The method can further include adjusting at least onecondition parameter to generate at least one condition, wherein eachcondition parameter may be associated with the at least one path andeach condition comprises devising a set of condition parameters to causethe animal to perform at least one of a symmetric locomotor task and anasymmetric locomotor task when the animal is forced to perform the atleast one walking campaign. The method can further include training theanimal on the device by at least acclimating the animal to the at leastone condition by causing the animal to perform the at least one walkingcampaign and/or at least one session of the at least one walkingcampaign. The method can further include performing the at least oneacclimation walking campaign and/or acclimation session until at leastone of appropriate or desired inter-stride lengths are achieved for eachcondition and locomotor standards for each condition are met. The methodcan further include causing the animal to perform the at least onewalking campaign on the device after the training, wherein each of theat least one walking campaigns is derived by generating randomizedwalking sessions. The method can further include recording data obtainedfrom the at least one walking campaign and performing data analysis ofthe data.

In some embodiments, constructing the device can further includegenerating a support framework configured as a square structure tosupport a plurality of pegs, the support framework comprising a firstside-length having a first path, a second side-length having a secondpath, a third side-length having a third path, and a fourth side-lengthhaving a fourth path. In some embodiments, generating the at least onecondition can further include generating first condition so that whenthe animal is forced to perform the at least one walking campaign, theanimal performs a symmetric locomotor task, generating a secondcondition so that when the animal is forced to perform the at least onewalking campaign, the animal performs a modified symmetric locomotortask, generating a third condition so that when the animal is forced toperform the at least one walking campaign, the animal performs aleft-side asymmetric locomotor task, and generating a fourth conditionso that when the animal is forced to perform the at least one walkingcampaign, the animal performs a right-side asymmetric locomotor task. Insome embodiments, generating the locomotor standards for the at leastone condition can include ensuring the animal is walking rather thanexhibiting other gaiting behavior. In some embodiments, the animal is arat. In some embodiments, the locomotive standards for the at least onecondition can include consistent walking without stops or missteps,minimal head-bobbing exhibited by the rat, a back of the rat beingarched and a tail of the rat being raised during locomotion, and eachlimb of the rat being clearly visible from an orthogonal view of thepath at an onset and an offset of a stance phase.

While these potential advantages are made possible by technicalsolutions offered herein, they are not required to be achieved. Thepresently disclosed device and method can be implemented to achievetechnical advantages, whether or not these potential advantages,individually or in combination, are sought or achieved.

Further features, aspects, objects, advantages, and possibleapplications of the present invention will become apparent from a studyof the exemplary embodiments and examples described below, incombination with the Figures, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, aspects, features, advantages and possibleapplications of the present invention will be more apparent from thefollowing more particular description thereof, presented in conjunctionwith the following Figures, in which:

FIG. 1 shows an exemplary support framework that may be used with theinventive device.

FIG. 2 shows an exemplary peg that may be used with the inventivedevice.

FIG. 3 shows one side-length that may be used with the support structureof FIG. 1.

FIG. 4 shows an exemplary electrical circuit that may be used togenerate a sensor array.

FIG. 5A shows an exemplary sensor enclosure that may be used with theinventive device. FIG. 5B shows an exemplary sensor enclosure that maybe used with the inventive device.

FIG. 6 is a block diagram showing an exemplary interconnection between asensor, a detection unit, an imaging device, and a computationalapparatus that may be used with the inventive device.

FIG. 7 is a top view of the support framework of FIG. 1.

FIG. 8 shows a flow diagram demonstrating an exemplary method of use ofthe inventive device.

FIG. 9A shows a schematic of a walkway that may be used for symmetricand asymmetric gait tasks. FIG. 9B shows a peg arrangement setting theright (rISL) inter-stride length and the left (lISL) inter-stride lengthin relation to the stride length (SL).

FIG. 10A shows the relationship between stance or swing phase duration(y-axis) and cycle duration (x-axis) for left-limb favored gait (L6R9)as represented by a regression analysis and a heat map of data pointdensity. FIG. 10B shows an asymmetry index for four conditions. FIG. 10Cshows diagonality indices (DIs) for four conditions.

FIG. 11A shows a heat map representing the distribution of stance orswing versus cycle duration for left-limb favored gait (L9R6). FIG. 11Bshows a calculated asymmetry index.

FIG. 12A shows an absolute difference in asymmetric indices (AI) betweenconditions L9R6 and L6R9. FIG. 12B shows an analysis of distribution ofdiagonality indices (DI) of four conditions.

DETAILED DESCRIPTION OF THE INVENTION

The following description is of an embodiment presently contemplated forcarrying out the present invention. This description is not to be takenin a limiting sense, but is made merely for the purpose of describingthe general principles and features of the present invention. The scopeof the present invention should be determined with reference to theclaims.

Spinal cord injury and/or stroke often produce asymmetric motordisability that reduces biomechanical efficiency. Rodents can be defacto models for the biomedical research of neural trauma; yet, artisanshave failed to provide systems and method that analyze the details ofsensorimotor control from rodent behavioral performance. To theknowledge of the inventors, no existing device or method prior to thisinvention can impose symmetric and asymmetric gaits with the stridelengths that span the range from preferred to critical unstable lengths.The presently disclosed devices and methods can further provide aneasy-to-learn task that can challenge stereotypical pathways of thespinal cord and/or the descending neural pathways responsible for theprecise limb placement.

Referring to FIGS. 1-2, the device can include a support framework 10structured to support a plurality of pegs 20. The support framework 10can be further structured as a walkway so as to accommodate an animalwalking along a path by stepping on the pegs 20. The path can be definedby the pegs 20 as the “floor” upon which the animal walks and by atleast one sidewall 30, directing the animal in at least one direction.In some embodiments, the support framework 10 can be structured togenerate a closed-loop walkway. This may include a walkway with a paththat feeds back into itself. In further embodiments, the path can beenclosed by a cover (e.g, domed, square, pyramidal, or other shapedstructure). The cover can be an enclosure disposed over the walkwaywhere the sides of the dome form the sidewalls 30. Alternatively, thecover can be an enclosure attached to the at least one sidewall 30 ofthe support framework 10. In at least one embodiment, any portion of thesidewalls 30 and/or cover can be transparent, translucent, or opaque.The transparent and/or translucent portions may be used to enable a userto observe the animal and/or record the animal via imaging and/or video.

Any one peg 20 can include an elongated staff section 22 with a platformsection 24. The platform section 24 can extend from a portion of thestaff section 22 and provide a surface upon which the animal's foot maybe placed. For example, the platform section 24 can extendperpendicularly from the staff section 22. In some embodiments, the peg20 may form an “L” shape with the long leg of the L being the staffsection 22 and the short leg of the L being the platform section 24. Anyone peg 20 can be affixed (attached to, secured within, and/orattachable to) a portion of the support framework 10. The affixment ofthe peg 20 to the support framework 10 can be permanent or temporary.Further, the affixment can be structured to enable adjustment of theplacement of the peg 20. Adjusting the placement can include, but is notlimited to, adjusting the peg 20 longitudinally (e.g., moving the peg 20in the z-direction), adjusting the peg 20 laterally (e.g., moving thepeg 20 in any one of the x-direction and y-direction), tilting the peg20, canting the peg 20, rotating the peg 20, etc. (See FIG. 3).

Referring to FIG. 3, the support framework 10 can include at least onesupport framework aperture 12 and the staff section 22 of the peg 20 caninclude at least one peg aperture 26. The peg 20 can be affixed to thesupport framework 10 by aligning a support framework aperture 12 with apeg aperture 26, wherein a fastener (e.g., pin) can then be insertedthrough the aligned apertures 12, 26. There can be sets of supportframework apertures 12, each set including a plurality of supportframework apertures 12. Each peg 20 can also have a plurality of pegapertures 26. The peg 20 can be adjusted longitudinally or laterally byaligning any aperture 26 within the sets of apertures 12. Adjusting thepeg 20 longitudinally in the positive z-direction can cause the platformsection 24 to be positioned at a higher elevation. Adjusting the peg 20longitudinally in the negative z-direction can cause the platformsection 24 to be positioned at a lower elevation. Similar adjustmentscan be made in the positive and negative x-directions and y-directions.

Other attachment mechanisms can be used. These may include a pin anddetent engagement, a clip engagement, a bayonet-style engagement, athreaded engagement, a telescopic engagement, etc. In some embodiments,placement of the peg 20 can be controlled by motor. For example, thestaff section 22 can include a toothed or splined surface. The supportframework 10 can include a motor in connection with a wormgear thatengages the splined surface and causes the peg 20 to move when thewormgear is caused to rotate. There can be a motor and wormgear for eachpeg 20. Other actuation means can be used to cause the mechanical and/orautomatic adjustment of the placement of any one peg 20. These mayinclude use of a gimbal and electro-mechanical motors, for example.Placement of the peg 20, and in particular placement of one peg 20relative to another peg 20, can be used to modify gait parameters and/orimpose step restrictions (e.g., stride length, intgerlimb phase,incline, etc.). Modifying gait parameters and/or imposing steprestrictions can facilitate analyzing details of sensorimotor control,facilitate imposing symmetric and asymmetric gaits with the stridelengths that span a range from preferred to critical unstable lengths,and/or facilitate challenging stereotypical pathways of the spinal cordand/or the descending neural pathways responsible for the precise limbplacement Adjusting the placement of any one peg 20 may also facilitateproviding perturbations for testing reflexes, such as H-reflexes forexample.

Any one peg 20 can be instrumented with at least one sensor 40 and/orelectro-mechanical switch. Any of the sensors 40 can be a contactsensor, a force-sensitive sensor, a pressure sensor, a motion sensor,etc. to detect foot placement by an animal on the platform section 24 ofa peg 20. The sensor 40 can be part of a sensor array, an exemplaryelectrical circuit of which is shown in FIG. 4. The output of thecircuit can be a Bayonet Neill-Concelman (BNC) connector to facilitateconnection/disconnection with a coaxial cable. The output may furtherfacilitate use with a radio frequency connection. The sensor array 40can include a two-part sensor enclosure 42, where the enclosure 42 caninclude a sensor housing pedestal 44 mountable to the platform section24 of a peg 20 and a rung component 46 fitted to slide into the sensorhousing pedestal 44. (See FIGS. 5A-5B). The sensor enclosure 42 canfurther include an extruded surface 48 to transfer force to the sensor40. In addition, or in the alternative, kinematic tracking techniquescan be used. These may include use of imaging devices 50, such asoptical cameras, video recorders, etc. to detect and record footplacement by an animal on the platform section 24 of a peg 20.

Referring back to FIG. 2, in at least one embodiment, each platformsection 24 of a peg 20 can include a sensor 40 and/or electro-mechanicalswitch that may be configured to transmit a signal when the platformsection 24 experiences in increase in pressure. The increase in pressuremay be due to placement of a foot by the animal on at least a portion ofthe platform section 24. Any one of the sensors 40 can be incommunication with a detection unit 60. The detection unit 60 may be aprocessor with a non-volatile, non-transitory, memory that can receiveand record signals transmitted by the sensor 40. In some embodiments,the signals from the sensor(s) 40 can be analog signals. The analogsignals may be sampled with a standard acquisition card (DAQ) forfurther quantitative analysis.

Use of the sensor(s) 40 and the detection unit(s) 60 can facilitatedetection and recordation of walking parameters. Walking parameters caninclude event data and statistical data associated with the animal'swalking campaign. A walking campaign can be one or more walking sessionsperformed by the animal on the device. Walking parameters can includetime of contact with the platform section 24, the number of times theplatform section 24 has been stepped on, pressure placed on the platformsection 24 by the animal while walking along the walkway, slippage fromthe platform section 24, etc. Detection and recordation of walkingparameters can facilitate evaluation of locomotion performance andtracking of corticospinal function before and after an animal suffers astroke and/or spinal cord injury.

Any surface of a platform section 24 can include a textured surfaceand/or coating that may provide a desired contact friction. This may bedone to challenge any preferential posture of the animal's posturalsystem. For example, an animal may exhibit a prefer posture of placingmore pressure on a left foot than a right foot while conducting awalking campaign. The contact friction of each platform section 24 wherethe animal is expected to make contact with its right foot can beprovided with a contact friction of cf-1, whereas each platform section24 where the animal is expected to make contact with its left foot canbe provided with a contact friction.

Any contact friction cf-i of one platform section 24 can be the same asor different from a contact friction cf-i of another platform section24.

Referring to FIG. 6, in some embodiments, the device can further includea computational apparatus 70, which may include a computer device and/orcomputer system. The computational apparatus 70 can include a processoroperatively associated with a non-transitory, non-volatile memory thatis configured to receive data from at least one of a sensor 40 and/or adetection unit 60 and process the data for analysis.

Some embodiments can include use of at least one imaging device 50 tocapture images and/or video of the animal's walking campaign. This mayinclude use of a high definition camera and/or video recorder. Theimaging device(s) 50 can be separate from the support framework 10 or beaffixed thereto. The same affixment means used for the pegs 20 can beused for the imaging device(s) 50. In some embodiments, the imagingdevice 50 captures images and/or video of the animal's walking campaignby viewing the animal through the transparent sidewall(s) 30. In otherwords, at least one imaging device 50 can be located at or near asidewall 30 to record at least a portion of the walking campaign throughthe sidewall 30. The imaging device(s) 50 can be configured to eitherproduce digital recordings and/or generate digital representations ofoptical recordings. The imaging device(s) 50 can be in communicationwith the computational apparatus 70 so as to transmit the digitalrecordings and/or digital representations of optical recordings to thecomputational apparatus 70 for further analysis. The imaging device(s)50 can further include a gimbal and electro-mechanical motors to causethe imaging device(s) 50 to rotate, pitch, and/or roll. The imagingdevice(s) 50 can further include motion sensors and automatic focusingsoftware to cause the imaging device(s) 50 to follow the animal as itperforms its walking campaign and to automatically focus the lens of theimaging device(s) 50.

Any of the communication links between components (sensors 40, imagingdevices 50, detection units 60, and/or computational apparatuses 70) ofthe invention can be via wireless and/or hardwire links. Where thecommunication between any two components is wireless, the components incommunication with each other may include transmitters, receivers,and/or transceivers to facilitate such communication.

Referring back to FIGS. 1-3, in at least one embodiment, the supportframework 10 can be structured as a square structure, where the squarestructure can have four side-lengths 14 (a first side-length 14′, asecond side-length 14″, a third side-length 14′″, and a fourthside-length 14″″). The support framework 10 can be supported by at leastone pillar 16. A pillar 16 can be located at each corner of the squarestructure. Each side-length 14 can include a beam 15 having an inneredge 15 a and an outer edge 15 b. A plurality of pegs 20 can be affixedto at least one side-length 14. For example, each staff section 22 canbe affixed to the beam 15 of the side-length 14 so that the platformsection 24 extends upward and away from the beam 15. Any side-length 14can include a plurality of pegs 20 affixed to the side-length beam 15 ofthat side-length 14. Any one peg 20 can be affixed to an inner edge 15 aor an outer edge 15 b of the side-length beam 15 of that side-length 14.Each peg 20 can be affixed to the side-length beam 15 of thatside-length 14 so that the platform section 24 extends upward and awayfrom the beam 15.

Any one side-length 14 can further include at least one sidewall 30. Thesidewall 30 can be a rectangular object that spans a length of theside-length 14 and have a height that effectively acts as a wall toguide the animal along the path that is along the side-length 14. Forexample, a sidewall 30 can be a rectangular sheet of metal, wood, glass,plastic, plexiglass, acrylic, fiberglass, etc. The support framework 10can include a first sidewall 30′ affixed to an outer edge 15 a of a beam15 of a side-length 14. The support framework 10 can include a secondsidewall 30″ affixed to an inner edge 15 b of a beam 15 of a side-length14. The same affixment means used for the pegs 20 can be used for anysidewall 30.

Any path of the support framework 10 can include a rest platform 18. Inat least one embodiment, at least one corner of the support framework 10can include a rest platform 18. The rest platform 18 may include asquare or rectangular plate that is large enough to allow the animal tostand upon securely in a stationary position to allow the animal torest. The rest platform 18 can be made of any material that is used forthe support framework 10. A first sidewall 30′ can be affixed outeredges of any of two opposing rest platforms 18 so that the firstsidewall 30′ spans a length of the side-length 14 between the twoopposing rest platforms 18. A second sidewall 30″ can be attached toinner edges of any of two opposing rest platforms so that the secondsidewall 30′ also spans the length of the side-length 14 between the twoopposing rest platforms 18. Thus, each side-length 14 can be providedwith a first sidewall 30′ and/or a second sidewall 30″, each spanningthe length of the side-length 14 between the two opposing rest platforms18.

A volume of space between the plurality of platform sections 24 arrangedalong a side-length 14 and the sidewall(s) 30 of the side-length 24 candefine the path. The plurality of pegs 20 of any side-length 14 can bestaggered so that each consecutive peg 20 is affixed to the inner andouter edges 15 a, 15 b, alternatively, of the side-length beam 15. Inother words, a first peg 20 may be affixed to the inner edge 15 a of theside-length beam 15, a second peg 20 may be affixed to the outer edge 15b of the side-length beam 15, a third peg 20 may be affixed to the inneredge 15 a of the side-length beam 15, and so on.

The plurality of pegs 20 of any side-length 14 can be configured so thateach platform section 24 has a space (d) between it and an adjacentplatform section 24. The spacing (d) between two adjacent platformsections 24 can be the same as or different from any other spacing (d)between any other two adjacent platform sections 24. Theheight-differential (h) between two adjacent platform sections 24 can bethe same as or different from any other height-differential (h) betweenany other two adjacent platform sections 24. Any of the peg 20placements (height, lateral placement, tilt, angle, etc.) can beadjusted. It is contemplated for the animal to walk along at least oneside-length 14 by stepping on the platform sections 24 to gain footing.For example, the animal can start at the first rest platform 18′ and becaused to walk along a first path of the first side-length 14′ bystepping on the platform sections 24 until it reaches the second restplatform 18″. The animal can continue to walk along a second path of thesecond side-length 14″ until it reaches the third rest platform 18′″.The animal can continue to walk along a third path of the thirdside-length 14′″ until it reaches the fourth rest platform 18′″. Theanimal can continue to walk along a fourth path of the fourthside-length 14″″ until it reaches the first rest platform 18′.

Referring to FIGS. 3 and 7, in some embodiments, the pegs 20 arrangedwithin a path can be configured so that the platform sections 24 providesalutary support for a left and a right foot. For example, each path caninclude a plurality of pegs 20 in a linear arrangement along the path.The path can further include a central pathway 1 running along itscenter between distal ends of a side-length 14. At least one peg 20 ofthe plurality of pegs 20 can be arranged such that its platform section24 is positioned to a first side of the central pathway 1. Further, atleast one peg 20 of the plurality of pegs 20 can be arranged such thatits platform section 24 is positioned to a second side of the centralpathway 1. When the animal is in the path and facing along a directionof the central pathway 1, the first side can be the same as theanatomical left side of the animal, and the second side can be the sameas the anatomical right side of the animal. In some embodiments, theplurality of pegs 20 in the linear array can be arranged such that eachadjacent platform section 24 alternates from being positioned on thefirst side to the second side. In other words, the plurality of pegs 20may be arranged such that the first platform section 24 is on the firstside, the second platform section 24 is on the second side, the thirdplatform section 24 is on the first side, and so on. This may be done tofacilitate a salutary flooring for walking. This may also force theanimal to place a left foot on a first-side positioned platform section24 and to place a right foot on a second-side positioned platformsection 24 as the animal walks along the path.

With an alternating first-side and second-side platform section 24arrangement between adjacent pegs 20, a distance between consecutiveplatform sections 24 on a same side can define a stride length (SL). Forexample, the distance between the first platform section 24 and thethird platform section 24 can be the SL between the first and thirdplatform sections 24. The SL between any two consecutive platformsections 24 can be the same as or different from the SL between anyother two consecutive platform sections 24. Further, the SL between anyone of the first-side positioned platform sections 24 can be the same asor different from the SL between any one of the second-side positionedplatform sections 24. Note, the spacing (d) may be referred to asinter-stride length.

Any of the supportive framework 10, rest platforms 18, sidewalls 30,and/or the pegs 20 may be fabricated from a rigid, support-bearingmaterial. This can include, but is not limited to metal, wood, plastic,glass, acrylic, etc. In at least one embodiment, any portion of thesupport framework 10, rest platforms 18, sidewalls 30, and/or pegs 20can be aluminum (e.g., 80/20 aluminum). A material of the supportframework 10 can be the same as or different from a material of the restplatforms 18, sidewalls 30, and/or pegs 20. Any material used for onepeg 20 can be the same as or different from a material of another thepeg 20. The support framework 10, rest platforms 18, sidewalls 30,and/or pegs 20 can be configured into a variety of shapes with a varietyof dimensions to accommodate different animals and research paradigms.For example, the support framework 10 can be a rectangular structurewith only one path. As another example, the support framework 10 can bea circular structure with one circular path, or one spiral path.Further, any of the paths can be straight, curved, zigzag, etc.

The distances (d), height-differentials (h), SL, contact friction, otherpeg 20 placement parameters, and additional variables can be used to setat least one condition. A condition can be a set of parameters used toevaluate locomotion performance, impose step restrictions, and/or trackcorticospinal function. For instance, a first set of parameters can be afirst condition, a second set of parameters can be a second condition,etc. A first condition may be a set of parameters that when the animalis forced to perform a walking campaign, causes the animal to perform asymmetric locomotor task. A second condition may be a set of parametersthat when the animal is forced to perform a walking campaign, causes theanimal to perform a modified symmetric locomotor task. A third conditionmay be a set of parameters that when the animal is forced to perform awalking campaign, causes the animal to perform a left-side asymmetriclocomotor task. A fourth condition may be a set of parameters that whenthe animal is forced to perform a walking campaign, causes the animal toperform a right-side asymmetric locomotor task. In some embodiments,each side-length 14 of the square structure can be individuallyconfigured to generate a condition-specific path. For example, the firstside-length 14′ may be configured to generate a first condition-specificpath, the second side-length 14″ may be configured to generate a secondcondition-specific path, the third side-length 14′″ may be configured togenerate a third condition-specific path, and the fourth side-length14″″ may be configured to generate a fourth condition-specific path.

In an exemplary embodiment, the device can be used with rats as theanimals to be tested upon. The device can include a support framework 10structured as an open-top plastic box braced with aluminum supports 16at each corner. Each aluminum support can have approximate dimensions of155×104 cm. Top edges of the box can be braced with aluminum barsgrooved on both sides to facilitate alternate peg 20 placement. Peg 20placement can be along a perimeter of the box. Each consecutive peg 20on the same side may define a SL. A rest platform 18 that isapproximately 20 cm×20 cm can be placed at each corner (four total),separating the conditions represented on each side-length 14. Eachside-length 14 can be a distance that is sufficient for the inclusion ofthe distance traversed by a single rat step cycle, as this distance maydefine the length of the walkway. For example, each side-length 14 canbe approximately 120 cm. Each side-length 14 can further include a firstsidewall 30′ along an outer edge 15 a of each side-length 14. Thesidewalls 14 can be transparent. Portions of the sidewalls 14 at eachcorner can be opaque. Pegs 20 made of aluminum with approximatedimensions of 20 cm×1 cm×0.5 cm and with a foot placement platform 24measuring approximately 2.5 cm can be secured to the grooved bars. Thiscan be done by using sliding inside brackets through machined holeslocated at a same distance to ensure level horizontal placement of eachplatform 24. Relative placement of the pegs 20 and/or platforms 24 maybe achieved with use of a screwdriver and a ruler. A 1 cm peg width, ora 1 cm platform section 24 width, can correspond approximately to anaverage rat paw size. A platform section 24 that is thinner or widerthan 1 cm may be either uncomfortable or increase foot placementvariability. A high definition camera 50 with a sampling rate of atleast 60 Hz can be used. The location of the high definition camera 50can be such that the placement of limbs on pegs 20 is unobstructed. Thehigh definition camera 50 can be configured to point perpendicularly tothe walkway with the field of view covering about 7 steps.

The device can be used to detect and record walking parameters, andfurther facilitate evaluation of locomotion performance of the animalconducting a walking campaign. A method of using the device can includeconstructing the device, generating at least one path. The method canfurther include adjusting at least one condition parameter to generate acondition. A separate condition can be generated for each path. In someembodiments, a plurality of paths can be generated. The plurality ofpaths can include a first path, a second path, a third path, and afourth path. Generating the first path can include defining the firstpath by the first condition. The first condition can include devising aset of parameters to cause the animal to perform a symmetric locomotortask when the animal is forced to perform a walking campaign. Generatingthe second path can include defining the second path by the secondcondition. The second condition can include devising a set of parametersto cause the animal to perform a modified symmetric locomotor task whenthe animal is forced to perform a walking campaign. Generating the thirdpath can include defining a third path by the third condition. The thirdcondition can include devising a set of parameters to cause the animalto perform a left-side asymmetric locomotor task when the animal isforced to perform a walking campaign. Generating the fourth path caninclude defining the fourth path by the fourth condition. The fourthcondition can include devising a set of parameters to cause the animalto perform a right-side asymmetric locomotor task when the animal isforced to perform a walking campaign.

The method can further include training the animal on the device. Thetraining may include acclimation of the animal to the at least onecondition by causing the animal to perform at least one walking campaignand/or at least one session of a walking campaign. A walking campaigncan be traversing a path for a minimal amount of times. The acclimationsessions can continue until appropriate or desired inter-stride lengthsare achieved for each condition. The appropriate or desired inter-stridelengths may be set by the experimenter, and can be based on the testbeing performed, the condition, the type of animal, etc. The acclimationsessions can further continue until locomotor standards for eachcondition are met. The locomotor standards may vary from animal toanimal, but the locomotor standards should be set such that the animalis clearly walking rather than exhibiting other gaiting behavior (e.g.,walking as opposed to galloping). The locomotor standards for rats, asan example, can include, but are not limited to: 1) consistent walkingwithout stops or missteps; 2) minimal head-bobbing is exhibited by theanimal; 3) the back is arched and the tail is raised during locomotion;and, 4) each limb is clearly visible from an orthogonal view of thewalkway at an onset and an offset of a stance phase.

The method can further include causing the animal to perform walkingcampaigns on the device after training. This can include randomizedwalking sessions within each walking campaign. The method can furtherinclude recordation of data and data analysis. The recordation of datacan include segmenting walking bouts (e.g., lengths along a path wherethe animal is walking) from other gaiting bouts (e.g., lengths along apath where the animal is gaiting in a manner other than walking). Dataassociated with the non-walking bouts may be excluded from the dataanalysis. The recordation of data can include identifying onsets andoffsets of kinematic phases. This can include identifying a time ofstance onset and a time of offset for each limb. Analyzing the data caninclude calculating a duration of swing phase, which can be a timeremaining between two consecutive kinematic stance onsets. The analyzingthe data can further include graphical representations of data andstatistical analysis (correlations, variance, linear regression, etc.).In some embodiments, the slope of a linear regression equation generatedfrom a linear regression analysis can be used to represent an amount ofchange in phase duration as a function of a change in speed oflocomotion. The analyzing the data can further include other statisticaland numerical analyses to generate variables representing at least oneof asymmetry index, horizontal difference, and vertical asymmetry. Inthe case of four-legged animals, the statistical variables can furtherinclude forelimb asymmetry, hind-limb asymmetry, left forelimb-hind-limbasymmetry, right forelimb-hind-limb asymmetry, diagonality indices, etc.

In an exemplary embodiment, the method can facilitate employment of thedevice for many uses. These may be imposing different locomotorbehaviors for basic science research. This may also be evaluatingmovement impairment in rodents used to model neurological,psychological, and/or musculoskeletal conditions. In particular, thedevice may be used for: tracking the corticospinal function before andafter stroke or spinal cord injury; tracking progression of diseasesthat cause movement impairment, e.g. Parkinson's, Alzheimer's, ALSsymptoms, blast trauma to cortex; and/o, tracking progression ofmovement disabilities in geriatric research.

Use of the device can solve and address the gap in the availability ofbehavioral research tools in rodents that focus on the movementevaluation. For example, the presently disclosed device and methods ofuse may enable researchers to impose a variety of behavioral tasks thatrange from stereotypical locomotion to precise limb placement in rodentsusing a task that may require minimal or no training of animals. Otheruses may include additional development of tracking and analysis tools.

The method of use can include a precise foot-placement locomotor taskthat evaluates cortical inputs to the spinal CPG. In addition, thedevice can be used to impose symmetrical and asymmetrical locomotortasks, which may be configured to mimic lateralized movement deficits.Using the device, the inventors have discovered that shifts fromequidistant inter-stride lengths of 20% can produce changes in theforelimb stance phase characteristics during locomotion with preferredstride length. Furthermore, the asymmetric walkway of the device canallow for measurements of behavioral outcomes produced by corticalcontrol signals. These measures may be relevant for the assessment ofimpairment after cortical damage.

The method can be a low-cost method for assessing the activity ofdescending cortical inputs in the motor system of quadruped animalsbased on a precise stepping locomotor task. The task can be designed tochallenge the motor cortex by imposing demands on foot placement over anatural range of walking speeds. In addition, foot-placementrequirements may be manipulated to preferentially challenge the left orright side of the animal's motor system. In a similar locomotor task,Metz & Whishaw (2009) examined the rates of failure, the number ofmissed steps on irregular rung walkway, in rats. Yet, the inventivemethod can be used to detail the quality of phase control in“successful” steps¹⁸.

Referring to FIGS. 9A-12B, an exemplary method was used as a trainingparadigm that employed the analysis of phase adjustments of the averageadult Sprague-Dawley rat. All procedures used within the exemplarytraining paradigm were performed in accordance with the InstitutionalAnimal Care and Use Committee (IACUC) and Office for Laboratory AnimalWelfare (OLAW) at West Virginia University School of Medicine and abidedby the National Institutes of Health guidelines for the use ofexperimental animals. The inventors employed the analysis of phaseduration characteristics¹⁷ that describes the relationship between theduration of swing or stance phases as a function of cycle duration ineach step. The obtained linear regression model was then furtherdescribed with an analysis of asymmetry across all limbs.

1. Exemplary Equipment Setup that May be Used with the ExemplaryTraining Paradigm Method

Referring to FIGS. 9A-9B, FIG. 9A shows a schematic of the walkway usedfor the symmetric and asymmetric gait tasks and FIG. 9B shows the peg 20arrangement setting the right (rISL) and left (lISL) inter-stridelengths in relation to the stride length (SL). The four conditionsincludes a symmetrical control locomotor task with 15 cm SL (SL15), asymmetrical locomotor task representing a 20% reduction in SL andpreferred speed (SL12), a left limb preferred (L9R6), and a right limbpreferred (L6R9) locomotor task.

1.1. Construct the asymmetric walkway as an open-top plastic box 10braced with aluminum supports 16 at each corner measuring 155 cm×104 cm.Brace the top edges of the box 10 with aluminum bars grooved on bothsides to allow for alternate peg 20 placement, along the perimeter ofthe box 16, so that each consecutive peg 20 on the same side defines theSL.

1.2. Place a 20 cm×20 cm platform 18 on each corner (four total)separating the conditions represented on each side 18. This distanceshould be sufficient for the inclusion of the distance traversed by asingle rat step cycle.

1.1.1. Use pegs 20 made of aluminum with dimensions of 20 cm×1 cm×0.5cm. Bend the top of each peg 20 at 2.5 cm from the tip to produce a footplacement platform 24.

1.1.2. Secure the pegs 20 to the grooved bars using sliding insidebrackets through machined holes at the same distance to ensure levelhorizontal placement. Adjust positions using a screwdriver and a ruler.Use a 1 cm peg width that corresponds approximately to the average ratpaw size; thinner or wider pegs are either uncomfortable or increase thefoot placement variability.

1.3. Manipulate the peg 20 placement on each side to produce one ofthree precise stepping challenge conditions.

1.4. Produce a symmetric locomotor task with a 15 cm stride length(SL15) by setting the left inter-stride length (lISL) and rightinter-stride length (rISL) to the half of stride length (7.5 cm). Anadditional symmetric condition (SL12) is imposed by lISL and rISLlengths of 6.0 cm.

1.5. Produce the asymmetric tasks by changing the distance between pegs20 on the left and right sides, termed the inter-stride length. Tochallenge the motor system asymmetrically, change the lISL and rISL by20% to impose short inter-stride lengths either on the left (L6R9condition) or on the right (L9R6) side. The 1.5 cm perturbations imposean lISL of 6 cm and rISL of 9 cm for the L6R9 condition, or an lISL of 9cm and a rISL of 6 cm for the L9R6 condition.

1.6. For rats, keep the stride length for all conditions except for SL12at a preferred 15 cm.

1.7. For convenience, assign each long side of the walkway an asymmetriccondition favoring either the left or the right side of the subject,while reserving the two short sides for the symmetric control condition.

1.8. Setup a high definition camera 50 with a sampling rate of at least60 Hz so that the placement of limbs on pegs 20 is unobstructed with thecamera 50 pointing perpendicularly to the walkway and with the field ofview covering about 7 steps. The first and last steps in proximity toplatforms 24 are ignored.

2. Exemplary Training on Device that May be Used with the ExemplaryTraining Paradigm Method

2.1. Please use standard training resources, e.g. NIH Training in BasicBiomethodology for Laboratory Rats, to familiarize with generalbehavioral training of rodents.

2.2. In the beginning of training, acclimate subjects by placing andrewarding them on the 20×20 cm platform 18 for at least 5 min. Then,guide the animals across a peg 20 arrangement with a 1 cm inter-stridelength to the next platform 18 by the presentation of a food reward.Reward animals verbally and with petting for reaching the platform 18.

2.3. After 5 training runs, space the pegs 20 an extra 1-2 cm apart andperform the next 5 training runs. The number of repetitions listedherein is sufficient to produce statistically appropriate sample size(20-35 steps).

2.1.1. If the animal acquires the task more slowly as judged byconsistency of stepping (no stopping) and posture (arched back), thenfocus training on the strengthening of these skills at the short stridelengths (S12) before resuming training on the long strides (S15)eventually approaching the desired stride length.

2.1.2. If the new spacing induces anxiety or discomfort with the task,readjust the pegs 20 to the previous setting and repeat the trainingparadigm.

2.1.3. Proceed with this training until the appropriate inter-stridelengths are achieved for the four conditions and locomotor standards aremet. In our experience, the rats responded well to vocal encouragementas cues for initiating a trial. The testing can be done on the same dayas training provided the subjects are motivated to perform the task.

Note: The locomotor standards are as follows: walking is consistent anddoes not involve stops or missteps; head-bobbing is minimal; the back isarched and the tail is raised during locomotion; each limb is clearlyvisible from an orthogonal view of the walkway at the onset and offsetof the stance phase. This selection process was essential as the presentstudy focused only on walking rather than other gaiting behavior.

3. Exemplary Testing and Data Analysis that May be Done with theExemplary Training Paradigm Method

Referring to FIGS. 10A-10C, FIG. 10A shows the relationship betweenstance or swing phase duration (y-axis) and cycle duration (x-axis) forleft-limb favored gait (L6R9) as represented by the regression analysisand a heat map of data point density. FIG. 10B shows asymmetry indexcalculated as shown in Equations (1) and (2), where r, l, a and p areslopes of the stance phase linear regressions for the right, left,anterior and posterior limbs, respectively. lAI_(v), rAI_(v), aAI_(h)and pAI_(h) are left-vertical, right vertical, fore-horizontal andhind-horizontal asymmetry indices, respectively, calculated for all fourconditions. FIG. 10C shows the diagonality indices (DIs) calculated asshown in Equation (3) for all four conditions lF, rF, lH and rH, whichare left forelimb, right forelimb, left hind-limb, and right hind-limbstance phase linear regression slopes, respectively. The phasecharacteristics were represented with the stance phase linearregressions using the slope-intercept equations. The insets correspondto the left forelimb (LF), right forelimb (RF), left hind-limb (LH) andright hind-limb (RH) heat maps.

3.1. Test animals on S12, S15, L9R6, and L6R9 tasks (described insection 1.5) using randomized session design. Use breaks to avoidadaptation within a task.

3.2. Import video recordings without re-sampling into video editingsoftware and select only the walking bouts for further analysis.

3.3. Mark onsets and offsets of kinematic phases in video recordingsfrom each subject.

3.4. Here, use the custom software called videoa written in Matlab® tomanually identify the time of stance onset and offset for each limb on aframe-by-frame basis, where stance onset is indicated by the loss ofmotion blur associated with the limb placement on a peg, and stanceoffset, occurring at the onset of limb lift-off, is indicated by thefirst evidence of motion blur.

3.5. Calculate the duration of swing phase as the time remaining betweentwo consecutive kinematic stance onsets. Exclude any behavior notconsistent with overground quadrupedal walking, e.g. when gait containsa double swing phase (both forelimbs or hind-limbs off the ground), fromproceeding analyses.

3.6. Plot the duration of each phase as a function of the correspondingstep cycle duration. Capture the relationship with the linear regressionmodel (Tphase=B1+B2*Tc) obtained for each limb, where Tc is cycleduration, Tphase is either Te extensor-related stance or Tf, which isthe flexor-related swing, and B1 and B2 are empirical constants (offsetand slope) of the regression model.

Note: The slope (B2) represents the amount of change in phase durationwith the change in speed of locomotion.

3.7. Use Equations 1 and 2 for each limb to calculate asymmetry index(AI). Both equations have the same form of a simple ratio thatnormalizes the difference of two values to their sum.AI_(h)=(r−1)/(r+1)  Equation (1):(a−p)/(a+p)  Equation (2):

3.1.1. Using Equation 1, calculate the horizontal difference (AI_(h))that uses the difference between slopes of stance modulation left (l)and right (r) limbs. Similarly, calculate the vertical asymmetry(AI_(v)) using the slopes from front/anterior (a) and back/posterior (p)limbs. The result of applying these two equations is the dataset of 4x-y points corresponding to 1) forelimb asymmetry, aAI_(h); 2) hind-limbasymmetry, pAI_(h); 3) left forelimb-hind-limb asymmetry, lAI_(v); 4)right forelimb-hind-limb asymmetry, rAI_(v).

3.1.2 Plot these values as a patch (see FIG. 10B) for the visualrepresentation of asymmetry across all limbs.

3.8. Calculate diagonality indices (DI) to assess diagonal couplingbetween parameters of a forelimb and its contralateral hind-limb byusing Equation 3 (see FIG. 10C).AI_(h)=[(rF+IH)−(IF+rH)]/[rF+IH+IF+rH].  Equation (3):

3.9. Test the DI, as well as the difference of four AIs betweenconditions of opposing asymmetry (ΔAI=|AIL9R6−AIL6R9|) for statisticalsignificance using a one-way ANOVA with the post-hoc comparison of meansanalysis.¹⁹

FIGS. 10A-10C show the analysis of asymmetry during the locomotor tasksfor a single representative subject. The values were calculated for allconditions using Equation 1 and 2 from all subjects individually andfrom composite data of 8 female Sprague-Dawley rats (250-400 g, seeFIGS. 11A-11B). Generally, the modulation of the forelimb stance phasewas lesser for the side to which the locomotion condition was favored(short ISL), consistent with the notion that the stance phase on thepreferred side (long ISL) tended to occupy a greater portion of the stepcycle as compared to the favored limb as the speed of locomotiondecreases.

The difference between corresponding asymmetry indices obtained fromconditions L9R6 and L6R9 (ΔAI) were tested with a one-way ANOVA (α=0.05)and post-hoc t-tests with conservative Bonferroni correction (adjustedα=0.0125) using anoval and multcompare functions in Matlab®. Overall,the difference between groups was significant (p=0.002). The anteriorhorizontal asymmetry index (ΔaAI_(h)) corresponding to the asymmetrybetween forelimbs was significantly different (p=0.006) between theleft-favored (L6R9) and the right-favored (L9R6) conditions. Thedifference between the conditions for the right vertical asymmetry index(ΔrAI_(v)) showed a trend, but it was not significantly different fromzero (p=0.031, α=0.0125). Similarly, the inventors found a significantdifference (p=0.020, α=0.05) in the diagonality index (DI) between twoasymmetric conditions. ANOVA testing found no differences between DI indifferent tasks, but there was only a single post-hoc t-test, whichrequired no additional alpha correction.

Referring to FIGS. 11A-11B, FIG. 11A shows a heat map representing thedistribution of stance or swing versus cycle duration for left-limbfavored gait (L9R6). The phase characteristics of the stance phaselinear regression were calculated, and are represented by theslope-intercept formula inset. FIG. 11 B shows the asymmetry indexcalculated. ΔlAI_(v), ΔrAI_(v), ΔaAI_(h) and ΔpAI_(h)—left-vertical,right vertical, anterior-horizontal and posterior-horizontal asymmetryindex differences, respectively, calculated for all four conditions asdescribed in Equation 3 by subtracting the corresponding asymmetryindices of the right-favored gait (L6R9) from the left-favored gait(L9R6) conditions. Asterisk—statistical significance as calculated bythe Bootstrap method.

Referring to FIGS. 12A-12B, FIG. 12A shows absolute difference inasymmetric indices (AI) between conditions L9R6 and L6R9 that weretested with one-way ANOVA with post-hoc t-test analysis adjusted withthe Bonferroni correction for multiple tests. The change in forelimbasymmetry (ΔaAI_(h)) between L9R6 and L6R9 was significant. FIG. 12Bshows an analysis of distribution of diagonality indices (DI) ofconditions S15, S12, L9R6 and L6R9 using one-way ANOVA with the post-hoct-test of the difference between asymmetric tasks (black).

As this method can be made to rely on the animals' natural ability tosolve the asymmetric foot placement, some animals may exhibitgallop-like behavior where the posterior limbs were simultaneously inswing. This gait was observed in three animals, and the behavior wasexcluded from further analyses.

The presently disclosed device and method sets forth a behavioral taskthat can quantitatively assess changes in precise control of asymmetriclocomotor behaviors. The existence of the spinal CPG has beenfunctionally demonstrated for some time²⁰, but the anatomical andfunctional characteristics that describe its mechanism as well as itsmodulatory inputs from descending or sensory feedback pathways have notbeen characterized until the past decade^(6,21,22). The currentconsensus is that the intrinsic spinal, sensory feedback, and descendingcommands are tightly integrated in the generation of locomotorbehavior.¹

The asymmetric precise foot placement task presented herein can befurther designed to functionally challenge the control systemsresponsible for the dexterous asymmetric control of stepping known torequire cortical inputs.^(23,24) This performance can be assessedrelative to the symmetric tasks that are less reliant on the descendingcortical and brainstem control. Thus, the device and method can enablediscerning the contributions of the spinal and descending pathways.Since the motor cortex is directly involved in the modulation of musclephases during locomotion, reaching, and postural adjustments^(9,10,25),the analysis of phase modulation in response to imposed asymmetricprecise stepping tasks may provide a basis for describing changes involitional control. This can be evident in the significant lateralizedphase modulation between left- and right-favored tasks, characterized bythe differences in asymmetry indices. The inventors have also observedchanges in whole body coordination that required diagonal couplingbetween contralateral forelimbs and hind-limbs, characterized bydifferences in the diagonal index.

Both focal stroke^(26,27) and spinal cord hemilesion^(28,29) animalmodels can cause mild to moderate movement deficits akin to thoseobserved clinically. With existing animal models, cortical lesioning ofthe corticospinal tract impedes or prevents precise stepping.^(30,31)The application of our methodology to the characterization of corticalimpairment in stroke models is yet to be described, though some of ourpreliminary data on rats with middle cerebral artery occlusions showedincreased AI, and even a negative slope of the stance phase withincreasing cycle duration for the limb on the side contralateral tostroke. This may correspond to a delay in the onset of consecutivelocomotor phases, which is consistent with an asymmetry in both the steplength ratio and the single limb support time observed in post-strokepatients.^(15,32)

A limitation of this method may be that it may be inappropriate for theanalysis of severely affected animals. However, this subgroup is notnecessarily the focus of attention in studies of hemiparetic animals.Furthermore, subjective tracking of this type of deficit may requireadditional sub scales that may also be associated with high inter-ratervariability, creating demand for gross computational methodology³³.Thus, the challenge remains not in the assessment of deficits in theseverely affected animals, but in the assessment of the mild to severesubgroup. Moreover, the ability to distinguish damage to specifichierarchical areas has been virtually impossible in a non-invasivemethod. Thus, the devices and methods of use disclosed herein can be aneffective tool for the evaluation of moderate impairment by monitoringmodulatory activity of the motor antagonistic phases that drive the CPGwith different speed demands, presumably contributed by higher orderfactors of the motor control hierarchy.⁶

It will be apparent to those skilled in the art that numerousmodifications and variations of the described examples and embodimentsare possible in light of the above teachings of the disclosure. Thedisclosed examples and embodiments are presented for purposes ofillustration only. Other alternate embodiments may include some or allof the features disclosed herein. Therefore, it is the intent to coverall such modifications and alternate embodiments as may come within thetrue scope of this invention, which is to be given the full breadththereof. While certain dimensions for elements have been disclosed here,such dimensions are exemplary only and other dimensions, both smallerand larger, are contemplated herein without departing from the spiritand scope of the invention. Additionally, the disclosure of a range ofvalues is a disclosure of every numerical value within that range,including the end points.

REFERENCES

-   1. Curzon, P., Zhang, M., Radek, R. J. & Fox, G. B. The Behavioral    Assessment of Sensorimotor Processes in the Mouse: Acoustic Startle,    Sensory Gating, Locomotor Activity, Rotarod, and Beam Walking. at    <http://www.ncbi.nlm.nih.gov/books/NBK5236/>(2009).-   2. Basso, D. M., Beattie, M. S. & Bresnahan, J. C. A sensitive and    reliable locomotor rating scale for open field testing in rats.    Journal of Neurotrauma 12 (1), 1-21 at    <http://www.ncbi.nlm.nih.gov/pubmed/7783230>(1995).-   3. Basso, D. M., Beattie, M. S. & Bresnahan, J. C. Graded    histological and locomotor outcomes after spinal cord contusion    using the NYU weight-drop device versus transection. Experimental    Neurology 139 (2), 244-56, doi:10.1006/exnr.1996.0098 (1996).-   4. Li, S., Shi, Z., et al. Assessing gait impairment after permanent    middle cerebral artery occlusion in rats using an automated    computer-aided control system. Behavioural Brain Research 250,    174-91, doi:10.1016/j.bbr.2013.04.044 (2013).-   5. Vandeputte, C., Taymans, J.-M., et al. Automated quantitative    gait analysis in animal models of movement disorders. BMC    Neuroscience 11, 92, doi:10.1186/1471-2202-11-92 (2010).-   6. Yakovenko, S. Chapter 10—A hierarchical perspective on rhythm    generation for locomotor control. Progress in Brain Research 188,    doi:10.1016/B978-0-444-53825-3.00015-2 (Elsevier BV.: 2011).-   7. Giszter, S. F., Hockensmith, G., Ramakrishnan, A. &    Udoekwere, U. I. How spinalized rats can walk: biomechanics, cortex    and hindlimb muscle scaling—implications for rehabilitation. Annals    of the New York Academy of Sciences 1198, 279-293,    doi:10.1111/j.1749-6632.2010.05534.x.How (2010).-   8. Smith, J. L., Edgerton, V. R., Eldred, E. & Zernicke, R. F. The    chronic spinalized cat: a model for neuromuscular plasticity. Birth    Defects Original Article Series 19 (4), 357-73 at    <http://www.ncbi.nlm.nih.gov/pubmed/6871404>(1983).-   9. Yakovenko, S. & Drew, T. A motor cortical contribution to the    anticipatory postural adjustments that precede reaching in the cat.    Journal of Neurophysiology 102 (2), 853-74,    doi:10.1152/jn.00042.2009 (2009).-   10. Yakovenko, S., Krouchev, N. & Drew, T. Sequential Activation of    Motor Cortical Neurons Contributes to Intralimb Coordination During    Reaching in the Cat by Modulating Muscle Synergies. Journal of    Neurophysiology 105, 388-409, doi:10.1152/jn.00469.2010. (2011).-   11. Pizzi, A., Carlucci, G., Falsini, C., Lunghi, F., Verdesca, S. &    Grippo, A. Gait in hemiplegia: Evaluation of clinical features with    the Wisconsin Gait Scale. Journal of Rehabilitation Medicine 39 (9),    170-174, doi:10.2340/16501977-0026 (2007).-   12. Bohannon, R. W., Horton, M. G. & Wikholm, J. B. Importance of    four variables of walking to patients with stroke. International    Journal of Rehabilitation Research 14 (3), 246-50 at    <http://www.ncbi.nlm.nih.gov/pubmed/1938039>(1991).-   13. Richards, C., Malouin, F., Dumas, F. & Tardif, D. Gait velocity    as an outcome measure of locomotor recovery after stroke. Gait    Analysis. Theory and Application, 355-364 (1995).-   14. Thaut, M. H., McIntosh, G. C. & Rice, R. R. Rhythmic    facilitation of gait training in hemiparetic stroke rehabilitation.    Journal of the Neurological Sciences 151, 207-212,    doi:10.1016/50022-510X(97)00146-9 (1997).-   15. Hsu, A.-L., Tang, P.-F. & Jan, M.-H. Analysis of impairments    influencing gait velocity and asymmetry of hemiplegic patients after    mild to moderate stroke. Archives of Physical Medicine and    Rehabilitation 84 (8), 1185-1193, doi:10.1016/S0003-9993(03)00030-3    (2003).-   16. Jansen, K., De Groote, F., Duysens, J. & Jonkers, I. Muscle    contributions to center of mass acceleration adapt to asymmetric    walking in healthy subjects. Gait & Posture 38 (4), 739-44,    doi:10.1016/j.gaitpost.2013.03.013 (2013).-   17. Halbertsma, J. M. The stride cycle of the cat: the modelling of    locomotion by computerized analysis of automatic recordings. Acta    physiologica Scandinavica 521, 1-75 at    <http://www.ncbi.nlm.nih.gov/pubmed/6582764>(1983).-   18. Metz, G. a & Whishaw, I. Q. The ladder rung walking task: a    scoring system and its practical application. Journal of Visualized    Experiments: JoVE (28), 4-7, doi:10.3791/1204 (2009).-   19. Hogg, R. V & Ledolter, J. Engineering Statistics. (MacMillan:    New York, N.Y., 1987).-   20. Brown, T. G. The intrinsic factors in the act of progression in    the mammal. Proceedings of the Royal Society of London. Series B,    Containing Papers of a Biological Character 84 (572), 308-319    (1911).-   21. Kiehn, O. Locomotor circuits in the mammalian spinal cord.    Annual Review of Neuroscience 29, 279-306,    doi:10.1146/annurev.neuro.29.051605.112910 (2006).-   22. Blitz, D. M. & Nusbaum, M. P. State-dependent presynaptic    inhibition regulates central pattern generator feedback to    descending inputs. The Journal of Neuroscience 28 (38), 9564-74,    doi:10.1523/JNEUROSCI.3011-08.2008 (2008).-   23. Martin, J. H. & Ghez, C. Red nucleus and motor cortex: parallel    motor systems for the initiation and control of skilled movement.    Behavioural Brain Research 28 (1-2), 217-23 at    <http://www.ncbi.nlm.nih.gov/pubmed/3382515>-   24. Drew, T., Jiang, W., Kably, B. & Lavoie, S. Role of the motor    cortex in the control of visually triggered gait modifications.    Canadian Journal of Physiology and Pharmacology 74 (4), 426-42 at    <http://www.ncbi.nlm.nih.gov/pubmed/8828889>(1996).-   25. Drew, T., Andujar, J.-E., Lajoie, K. & Yakovenko, S. Cortical    mechanisms involved in visuomotor coordination during precision    walking. Brain Research Reviews 57 (1), 199-211,    doi:10.1016/j.brainresrev.2007.07.017 (2008).-   26. Longa, E. Z., Weinstein, P. R., Carlson, S. & Cummins, R.    Reversible middle cerebral artery occlusion without craniectomy in    rats. Stroke 20 (1), 84-91, doi:10.1161/01.STR.20.1.84 (1989).-   27. Uluç, K., Miranpuri, A., Kujoth, G. C., Aktüre, E. &    Başkaya, M. K. Focal Cerebral Ischemia Model by Endovascular Suture    Occlusion of the Middle Cerebral Artery in the Rat. Journal of    Visualized Experiments: JoVE 48 (e1978), 1-5, doi:10.3791/1978    (2011).-   28. Hackney, D. B., Finkelstein, S. D., Hand, C. M.,    Markowitz, R. S. & Black, P. Postmortem Magnetic Resonance Imaging    of Experimental Spinal Cord Injury: Magnetic Resonance Findings    versus In Vivo Functional Deficit. Neurosurgery 35 (6), 1104-1111    (1994).-   29. Kjaerulff, O. & Kiehn, O. Distribution of Networks Generating    and Coordinating Locomotor Activity in the Neonatal Rat Spinal Cord    In Vitro: A Lesion Study. The Journal of Neuroscience 16 (18),    5777-5794 (1996).-   30. Liddell, E. G. T. & Phillips, C. G. Striatal and pyramidal    lesions in the cat. Brain 69 (4), 264-279,    doi:10.1093/brain/69.4.264 (1946).-   31. Beloozerova, I. N. & Sirota, M. G. The Role of the Motor Cortex    in the Control of Accuracy of Locomotor Movements in the Cat.    Journal of Physiology 461, 1-25 (1993).-   32. Hill, K. D., Goldie, P. A., Baker, P. A. & Greenwood, K. M.    Retest reliability of the temporal and distance characteristics of    hemiplegic gait using a footswitch system. Archives of Physical    Medicine and Rehabilitation 75 (5), 577-83 at    <http://www.ncbi.nlm.nih.gov/pubmed/8185453>(1994).-   33. Hillyer, J. E. & Joynes, R. L. A new measure of hindlimb    stepping ability in neonatally spinalized rats. Behavioural Brain    Research 202 (2), 291-302, doi: 10.1016/j.bbr.2009.04.009 (2009).

What is claimed is:
 1. A method for quantitatively assessing the changesin control of asymmetric locomotor behavior of an animal comprisinganalyzing the phase modulation in response to one or more of an imposedasymmetric stepping task wherein either a right inter-stride length, ora left inter-stride length, or a combination of said right inter-stridelength and said left inter-stride length of said animal, are adjusted inrelation to stride-length for quantitatively assessing changes incontrol of asymmetric locomotor behavior, and observing changes in wholebody coordination of said animal requiring diagonal coupling betweencontralateral forelimbs and hind-limbs of said animal characterized bydifferences in diagonal angle.
 2. The method of claim 1, furthercomprising providing an animal having either a focal stroke or spinalcord hemilesion.
 3. A device for quantitative analysis of gait,comprising: a support framework structured to support a plurality ofpegs, the plurality of pegs forming a walkway to accommodate an animalwalking along the plurality of pegs, the walkway comprising a firstdistal end and a second distal end; a rest platform located at each ofthe first distal end and the second distal end; a path defined by thewalkway, the path comprising a central pathway running along its centerfrom the first distal end to the second distal end forming a path firstside and a path second side; and at least one sensor and at least onedetection unit associated with at least one peg, the at least one sensorgenerating a signal when a foot by the animal is placed on the at leastone peg and transmitting the signal to the detection unit, the detectionunit detecting placement of the foot by the animal on the at least onepeg; wherein each peg comprises a platform section upon which the animalplaces the foot when walking along the path; wherein the plurality ofpegs is arranged in a linear array along the path and each peg isarranged in a staggered manner so that the platform section of eachadjacent peg in the linear array is located on an opposite side of thecentral pathway; wherein a distance between each adjacent platformsection is (d) and a distance between each consecutive platform sectionof a same side of the central pathway is a stride-length (SL); andwherein placement of each peg relative to other pegs and relative to thesupport framework is adjustable.
 4. A device for quantitative analysisof gait, comprising: a support framework configured as a squarestructure to support a plurality of pegs, the support frameworkcomprising a first side-length, a second side-length, a thirdside-length, and a fourth side-length, the plurality of pegs forming awalkway along each side-length to accommodate an animal walking alongthe plurality of pegs, each walkway comprising a distal end located ateach corner of the support framework; a rest platform located at eachcorner; a path defined by each walkway, the path comprising a centralpathway running along its center from the distal ends of each walkwayforming a path first side and a path second side; and at least onesensor and at least one detection unit associated with at least one pegwithin each walkway, the at least one sensor generating a signal when afoot by the animal is placed on the at least one peg and transmittingthe signal to the detection unit, the detection unit detecting placementof the foot by the animal on the at least one peg; wherein each pegcomprises a platform section upon which the animal places the foot whenwalking along the path; wherein the plurality of pegs is arranged in alinear array along the path and each peg is arranged in a staggeredmanner so that the platform section of each adjacent peg in the lineararray is located on an opposite side of the central pathway; wherein adistance between each adjacent platform section is (d) and a distancebetween each consecutive platform section of a same side of the centralpathway is a stride-length (SL); wherein placement of each peg relativeto other pegs and relative to the support framework is adjustable; andwherein the (d) and the (SL) on an individual path are at least twoparameters that define a condition.
 5. The device of claim 4 wherein:the condition for the path of the first side-length is different fromthe condition for the path of the second side-length, the condition forthe path of the third side-length, and the condition for the path of thefourth side-length; the condition for the path of the second side-lengthis different from the condition for the path of the first side-length,the condition for the path of the third side-length, and the conditionfor the path of the fourth side-length; the condition for the path ofthe third side-length is different from the condition for the path ofthe first side-length, the condition for the path of the secondside-length, and the condition for the path of the fourth side-length;and the condition for the path of the fourth side-length is differentfrom the condition for the path of the first side-length, the conditionfor the path of the second side-length, and the condition for the pathof the third side-length.
 6. The device of claim 4, wherein thecondition is a set of parameters to evaluate locomotion performance,impose step restrictions, and/or track corticospinal function.
 7. Thedevice of claim 4, including an imaging device that is capable ofcapturing images of said framework, each of said rest platforms, saidwalkway, and said path.
 8. The device of claim 7, wherein said imagingdevice is in communication with a computational apparatus for analyzingone or more images captured by said imaging device.
 9. The device ofclaim 7, wherein said imaging device is a camera that is a pointed atsaid framework, each of said rest platforms, said walkway, and saidpath.
 10. The device of claim 9, wherein said camera is a video camera.